Multilayer ceramic capacitor

ABSTRACT

A multilayer ceramic capacitor includes an external electrode on an end surface of a ceramic body to be connected to internal electrodes including a base layer including a sintered metal containing Cu and glass and a Cu plated layer on the base layer. The external electrode includes a principal surface portion disposed on a principal surface of the ceramic body. The Cu metal of the Cu plated layer is present in the base layer to a position of about ⅓ or more of the thickness of the base layer from a surface layer of the external electrode. The metal thickness of the external electrode is about 8.7 μm or more and about 13.9 μm or less.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multilayer ceramic capacitor.

2. Description of the Related Art

In recent years, with the reduction in size and height for electronicdevices such as cellular phones and portable music players, multilayerprinted wiring boards mounted on the electronic devices have beenprogressively reduced in size. Accordingly, multilayer ceramiccapacitors mounted on the multilayer printed wiring boards have beenalso progressively reduced in size and height.

Some of the multilayer ceramic capacitors are built into multilayerprinted wiring boards, such as the multilayer ceramic capacitordescribed in, for example, Japanese Patent Application Laid-Open No.2002-203735. In the case of building the multilayer ceramic capacitorinto Japanese Patent Application Laid-Open No. 2002-203735, there is aneed to irradiate external electrodes of the multilayer ceramiccapacitor with a laser to form opening for via holes in order toelectrically connect the capacitor to the multilayer printed wiringboard.

However, the external electrodes preferably have laser resistance in thecase of irradiating the external electrodes of the multilayer ceramiccapacitor with a laser in order to form the openings for via holes. Thisis because the external electrodes may be damaged unless the electrodeshave laser resistance.

Moreover, if the multilayer ceramic capacitor to be built into amultilayer printed wiring board has large differences in level betweenthe surface of the ceramic body and the surfaces of the externalelectrodes, the gap between the surface of the multilayer printed wiringboard and the mounting surface of the ceramic body is widened when thecapacitor is built in the multilayer printed wiring board. Therefore,peeling is likely to be caused between the multilayer printed wiringboard and the external electrodes, and there is also a problem ofmoisture ingress from the peeled sites, which results in degradedresistance to moisture.

SUMMARY OF THE INVENTION

Therefore, preferred embodiments of the present invention provide amultilayer ceramic capacitor with an external electrode that hasexcellent laser resistance and moisture resistance.

The multilayer ceramic capacitor according to a preferred embodiment ofthe present invention is a multilayer ceramic capacitor including aceramic body with a plurality of ceramic layers and internal electrodesstacked, which includes principal surfaces opposed to each other, sidesurfaces opposed to each other, and end surfaces opposed to each other;and an external electrode including a base layer including a sinteredmetal containing Cu and glass and a Cu plated layer provided on asurface of the base layer, which is provided on one of the end surfacesof the ceramic body to be connected to the internal electrodes, wherethe external electrode includes a principal surface portion disposed onone of the principal surfaces of the ceramic body, the Cu metal of theCu plated layer is present in the base layer to a position of about ⅓ ormore of a thickness of the base layer from a surface layer of theexternal electrode, and the external electrode is about 8.7 μm or moreand about 13.9 μm or less in metal thickness.

Furthermore, the multilayer ceramic capacitor is preferably about 0.9 mmor more and about 1.1 mm or less in dimension in a direction ofconnecting the end surfaces to each other, about 0.4 mm or more andabout 0.6 mm or less in dimension in a direction of connecting the sidesurfaces to each other, and about 0.085 mm or more and about 0.15 mm orless in dimension in a direction of connecting the principal surfaces toeach other.

In addition, in a multilayer ceramic capacitor according to a preferredembodiment of the present invention, the Cu plated layer is preferablyformed with the use of any of a pyrophosphoric acid Cu plating solutionand a cyanide Cu plating solution.

Furthermore, in a multilayer ceramic capacitor according to a preferredembodiment of the present invention, the glass contained in the baselayer is preferably composed of glass containing BaO in an amount ofabout 10 weight % or more and about 50 weight % or less, SrO in anamount of about 10 weight % or more and about 50 weight % or less, B₂O₃in an amount of about 3 weight % or more and about 30 weight % or less,and SiO₂ in an amount of about 3 weight % or more and about 30 weight %or less.

When the low-reflectance glass component contained in the base layer isdirectly irradiated with a laser, the base layer of the sintered metalcontaining Cu and glass will absorb the energy of the laser to decreasethe laser resistance. Accordingly, the Cu plated layer preferablydefines an outermost layer of the external electrode. More specifically,the laser resistance of the external electrode is determined by thetotal amount of Cu contained in the base layer and Cu of the Cu platedlayer.

According to a preferred embodiment of the present invention, the glasscontained in the base layer is dissolved to cause the Cu metal of the Cuplated layer to penetrate in the base layer to a position of about ⅓ ormore of the thickness of the base layer from the surface layer of theexternal electrode, and the Cu content rate is high in the base layer.Accordingly, in combination with the base layer and Cu plated layer intotal, the content rate of Cu per unit thickness is increased to improvethe thermal conductivity (heat release performance) of the base layerand increase the laser resistance of the external electrode.

In addition, in a preferred embodiment of the present invention, adifference in level between the surface of the multilayer printed wiringboard and the surface of the external electrode is reduced because theexternal electrode including the base layer and the Cu plated layer isreduced in total thickness (the metal thickness of the externalelectrode is about 8.7 μm or more and about 13.9 μm or less). As aresult, the gap between the surface of the multilayer printed wiringboard and the mounting surface of the ceramic body is narrowed to makepeeling less likely to be caused between the multilayer printed wiringboard and the external electrode and also improve the mechanicalstrength of the component. It is to be noted that the metal thicknessrefers to a value obtained by measuring the thickness of the metal witha fluorescent X-ray film thickness meter, and converting the measuredX-ray Cu amount into a film thickness.

Furthermore, in a preferred embodiment of the present invention, when apyrophosphoric acid Cu plating solution or a cyanide Cu plating solutionis used as the plating solution for forming the Cu plated layer, theplating solution with high glass erosion capability, efficientlydissolves the glass contained in the base layer, and easily cause the Cumetal of the Cu plated layer to penetrate into the base layer, thusimproving the content rate of Cu in the base layer.

Furthermore, in a preferred embodiment of the present invention, whenthe glass contained in the base layer includes glass containing BaO inan amount of about 10 weight % or more and about 50 weight % or less,SrO in an amount of about 10 weight % or more and about 50 weight % orless, B₂O₃ in an amount of about 3 weight % or more and about 30 weight% or less, and SiO₂ in an amount of about 3 weight % or more and about30 weight % or less, the glass contained in the base layer is dissolvedreliably.

According to a preferred embodiment of the present invention, the Cumetal of the Cu plated layer penetrates in the base layer to a positionof about ⅓ or more of the base electrode thickness from the surfacelayer of the external electrode. Thus, the Cu content rate in the baselayer is increased, and the thermal conductivity (heat releaseperformance) of the base layer is improved to increase the laserresistance of the external electrode. In addition, the difference inlevel between the surface of the multilayer printed wiring board and thesurface of the external electrode is reduced because the externalelectrode including the base layer and the Cu plated layer is reduced intotal thickness (for example, the metal thickness of the externalelectrode on average preferably is about 8.7 μm or more and about 13.9μm or less). As a result, the narrowed gap between the surface of themultilayer printed wiring board and the mounting surface of the ceramicbody significantly reduces or prevents peeling between the multilayerprinted wiring board and the external electrode.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an example of a multilayerceramic capacitor according to a preferred embodiment of the presentinvention.

FIG. 2 is a side view of the multilayer ceramic capacitor shown in FIG.1.

FIG. 3 is a cross-sectional view along line III-III of FIG. 1.

FIG. 4 is a schematic cross-sectional view illustrating a metal of a Cuplated layer of an external electrode, which penetrates into a baselayer.

FIG. 5 is a drawing illustrating a preferred embodiment of a multilayerceramic capacitor according to the present invention, which is able toachieve a greater effect, specifically, an explanatory drawing forschematically explaining a maximum thickness D_(max) and an averagethickness D_(ave) of a principal surface portion.

FIG. 6 is a schematic drawing for explaining the shape of an externalelectrode of a multilayer ceramic capacitor according to a preferredembodiment of the present invention, which is able to achieve a greatereffect.

FIG. 7 shows a cross-sectional view of a preferred embodiment of amultilayer ceramic capacitor according to the present invention, whichis able to achieve a greater effect, along the line III-III of FIG. 1.

FIG. 8 shows a cross-sectional view of a preferred embodiment of amultilayer ceramic capacitor according to the present invention, whichis able to achieve a greater effect, along the line III-III of FIG. 1.

FIG. 9 shows a cross-sectional view of a preferred embodiment of amultilayer ceramic capacitor according to the present invention, whichis able to achieve a greater effect, along the line III-III of FIG. 1.

FIG. 10 shows a cross-sectional view of a preferred embodiment of amultilayer ceramic capacitor according to the present invention, whichis able to achieve a greater effect, along the line III-III of FIG. 1.

FIG. 11 shows a cross-sectional view of a preferred embodiment of amultilayer ceramic capacitor according to the present invention, whichis able to achieve a greater effect, along the line III-III of FIG. 1.

FIG. 12 shows a cross-sectional view of a preferred embodiment of amultilayer ceramic capacitor according to the present invention, whichis able to achieve a greater effect, along the line III-III of FIG. 1.

FIGS. 13A and 13B are plan views of multilayer ceramic capacitors, whichillustrate the shapes of edge ends of external electrodes provided onprincipal surfaces of ceramic bodies.

FIG. 14 is a flowchart showing an example of a method for manufacturingthe multilayer ceramic capacitor shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is an external perspective view illustrating a multilayer ceramiccapacitor 10. FIG. 2 is a side view of the multilayer ceramic capacitor10 shown in FIG. 1. FIG. 3 is a cross-sectional view along line III-IIIof FIG. 1.

The multilayer ceramic capacitor 10 shown in FIG. 1 includes a ceramicbody 12, for example, in the form of a cuboid. This multilayer ceramiccapacitor 10 is mostly a multilayer ceramic capacitor built in amultilayer printed wiring board. The ceramic body 12 includes aplurality of ceramic layers 14 stacked. The ceramic body 12 includes apair of principal surfaces 12 a, 12 b opposed to each other, a pair ofside surfaces 12 c, 12 d opposed to each other, and a pair of endsurfaces 12 e, 12 f opposed to each other.

The principal surfaces 12 a, 12 b are each arranged in a lengthdirection L and a width direction W.

The side surfaces 12 c, 12 d are each arranged in the length direction Land a height direction T.

The end surfaces 12 e, 12 f are each arranged in the width direction Wand the height direction T.

Therefore, the length direction L refers to a direction of connectingthe pair of end surfaces 12 e, 12 f to each other, the width direction Wrefers to a direction of connecting the pair of side surfaces 12 c, 12 dto each other, and the height direction T refers to a direction ofconnecting the pair of principal surfaces 12 a, 12 b to each other.

It is to be noted that while the multilayer ceramic capacitor 10according to this preferred embodiment preferably has a cuboid shape,the shape of the ceramic body 12 is not particularly limited.

In addition, the ceramic body 12 preferably has corners and ridgesrounded.

The ceramic layers 14 of the ceramic body 12 can be formed from adielectric ceramic material. As the dielectric ceramic material for theceramic layers 14, a dielectric ceramic can be used which contains amain constituent such as, for example, BaTiO₃, CaTiO₃, SrTiO₃, andCaZrO₃. Furthermore, depending on desired characteristics of themultilayer ceramic capacitor 10, the main constituents may be used towhich accessory constituents are added such as Mn compounds, Mgcompounds, Si compounds, Fe compounds, Cr compounds, Co compounds, Nicompounds, rare-earth compounds.

Furthermore, the ceramic layers 14 are preferably about 0.5 μm or moreand about 10 μm or less in height.

In this preferred embodiment, for each effective portion of the ceramicbody 12, opposed portions 18 a, 18 b of internal electrodes 16 a, 16 bto be described are opposed with the ceramic layers 14 of the dielectricceramic interposed therebetween to generate electrostatic capacitance.Thus, this preferred embodiment defines and functions as a capacitor.

Within the ceramic body 12, a plurality of substantially rectangularfirst internal electrodes 16 a and second internal electrodes 16 b arealternately arranged at regular intervals in the height direction T ofthe ceramic body 12.

The first internal electrodes 16 a include the opposed portions 18 a andextended portions 20 a. The opposed portions 18 a are opposed to thesecond internal electrodes 16 b. The extended portions 20 a are exposedby extending from the opposed portions 18 a to the end surface 12 e ofthe ceramic body 12, but not exposed at the end surface 12 f or the sidesurfaces 12 c, 12 d.

The second internal electrodes 16 b include the opposed portions 18 band extended portions 20 b as in the case of the first internalelectrodes 16 a. The opposed portions 18 b are opposed to the firstinternal electrodes 16 a. The extended portions 20 b are extended fromthe opposed portions 18 b to the end surface 12 f of the ceramic body12, but not exposed at the end surface 12 e or the side surfaces 12 c,12 d.

Furthermore, the first internal electrodes 16 a and the second internalelectrodes 16 b are each parallel or substantially parallel to theprincipal surface 12 a and principal surface 12 b of the ceramic body12. In addition, the first internal electrodes 16 a and the secondinternal electrodes 16 b are opposed to each other with the ceramiclayers 14 interposed therebetween in the height direction T of theceramic body 12.

The internal electrodes 16 a, 16 b are each, for example, about 0.2 μmor more and about 2 μm or less in height. The internal electrodes 16 a,16 b can be composed of an appropriate conductive material. The internalelectrodes 16 a, 16 b can be composed of, for example, a metal such asNi, Cu, Ag, Pd, and Au, or an alloy containing one of the metals, suchas, for example, an Ag—Pd alloy.

In this regard, the respective metals of the first internal electrodes16 a and second internal electrodes 16 b are preferably diffused in afirst external electrode 22 a and a second external electrode 22 b asdescribed later. The metal of the first internal electrode 16 a diffusesinto the first external electrode 22 a to expand the volume of the metalin the first external electrode 22 a and fill minute gaps in the firstexternal electrode 22 a, thus making it possible improve the sealingproperty against ingress of moisture. Likewise, the metal of the secondinternal electrode 16 b diffuses into the second external electrode 22 bto expand the volume of the metal in the second external electrode 22 band fill minute gaps in the second external electrode 22 b, thus makingit possible improve the sealing property against ingress of moisture. Itis to be noted that the diffusion distances of the metals of theinternal electrodes 16 a, 16 b into the external electrodes 22 a, 22 bare preferably about 4 μm or more.

In addition, glass layers may be formed on exposed portions where theextended portions 20 a, 20 b of the internal electrodes 16 a, 16 b areexposed at the end surfaces 12 e, 12 f of the ceramic body 12. Theformation of the glass layers on the exposed portions of the internalelectrodes 16 a, 16 b ensure moisture resistance and plating resistance,and suppress or prevent ingress of moisture from the outside, even whenthe external electrodes 22 a, 22 b to be described are insufficientlydense. As a result, the moisture resistance and plating resistance ofthe multilayer ceramic capacitor 10 are improved.

The first external electrode 22 a and the second external electrode 22 bare respectively provided on the end surfaces 12 e, 12 f of the ceramicbody 12. The first external electrode 22 a is electrically connectedthrough the extended portions 20 a to the first internal electrodes 16 aat the end surface 12 e. In addition, the first external electrode 22 ais provided on the principal surfaces so as to partially cover theprincipal surfaces 12 a, 12 b and the side surfaces 12 c, 12 d from thesurface of the end surface 12 e. The second external electrode 22 b iselectrically connected through the extended portions 20 b to the secondinternal electrodes 16 b at the end surface 12 f. In addition, thesecond external electrode 22 b is provided on the principal surfaces soas to partially cover the principal surfaces 12 a, 12 b and the sidesurfaces 12 c, 12 d from the surface of the end surface 12 f.

The first external electrode 22 a includes a base layer 24 a and aplated layer 26 a provided on the surface of the base layer 24 a.Furthermore, the second external electrode 22 b includes a base layer 24b and a plated layer 26 b provided on the surface of the base layer 24b.

The base layers 24 a, 24 b include a sintered metal containing Cu andglass. The base layers 24 a, 24 b may be co-fired by co-firing with theinternal electrodes 16 a, 16 b, or post-fired by baking a conductivepaste applied. The base layers 24 a, 24 b are preferably about 1 μm ormore and about 20 μm or less in thickness.

The plated layers 26 a, 26 b may include a plurality of layers formed.The material constituting the outermost plated layers 26 a, 26 bincludes a Cu plated film. The plated layers 26 a, 26 b are preferablyabout 1 μm or more and about 10 μm or less in thickness. When theoutermost layers include a Cu plated film, it becomes possible to usethe multilayer ceramic capacitor 10 as an electronic component built ina multilayer printed wiring board.

More specifically, in the case of embedding the multilayer ceramiccapacitor 10 into a multilayer printed wiring board, there is a need toprovide via holes for electronic component connection in the multilayerprinted wiring board, in order to provide electrical connection to theexternal electrode 22 a, 22 b. The via holes for electronic componentconnection are formed with the use of a laser such as a CO₂ laser, forexample. In the case of forming the via holes with the use of a laser,the first external electrodes 22 a, 22 b of the multilayer ceramiccapacitor 10 are directly irradiated with the laser. In this regard,when the outermost layers of the plated layers 26 a, 26 b of theexternal electrodes 22 a, 22 b include a Cu plated film, the laser isreflected at a high reflectance, and the capacitor is thus about to beused in a preferred manner as the multilayer ceramic capacitor 10 to beembedded in the multilayer printed wiring board. This is because whenthe laser reflectance is low with respect to the external electrodes 22a, 22 b of the multilayer ceramic capacitor 10, the laser may reach eventhe inside of the multilayer ceramic capacitor 10, and damage themultilayer ceramic capacitor 10.

In this regard, when the plated layers 26 a, 26 b are entirely composedof Cu, the Cu metal of the plated layers 26 a, 26 b is present in thebase layers 24 a, 24 b to a position of about ⅓ or more of thethicknesses of the base layers 24 a, 24 b respectively from the surfacelayers of the base layers 24 a, 24 b, as shown in FIG. 4. Further, inregard to penetration of the Cu metal of the Cu plated layers 26 a, 26 binto the base layers 24 a, 24 b, the Cu metal of the plated layers 26 a,26 b is preferably present at about 30% or more with respect to thetotal proportion of the Cu metal of the base layers 24 a, 24 b andplated layers 26 a, 26 b on lines, when the lines are drawn along theportion of about ⅓ in thickness from the surface layers of the baselayers 24 a, 24 b in any observation field of view of about 30 μm inx-axis and about 30 μm in y-axis, including the base layers 24 a, 24 bformed on the principal surfaces of the ceramic body at a polishedsurface obtained by polishing the side surface (surface LT) of themultilayer ceramic capacitor 10 along the length direction L untilreaching about ½ the dimension in the width direction W.

More specifically, the Cu plated layers 26 a, 26 b preferably are formedwith the use of a pyrophosphoric acid Cu plating solution or a cyanideCu plating solution, for example. These plating solutions with highglass erosion capability, efficiently dissolve the glass contained inthe base layer 24 a, 24 b, and easily cause the Cu metal of the Cuplated layers 26 a, 26 b to penetrate into the base layer 24 a, 24 b,thus making it possible to improve the content rate of Cu in the baselayers 24 a, 24 b.

In this regard, the glass in the base layers 24 a, 24 b is preferablycomposed of glass containing BaO in an amount of about 10 weight % ormore and about 50 weight % or less, SrO in an amount of about 10 weight% or more and about 50 weight % or less, B₂O₃ in an amount of about 3weight % or more and about 30 weight % or less, and SiO₂ in an amount ofabout 3 weight % or more and about 30 weight % or less. Thus, in theformation of the Cu plated layers 26 a, 26 b with the use of apyrophosphoric acid Cu plating solution or a cyanide Cu platingsolution, for example, the glass contained in the base layers 24 a, 24 bis dissolved reliably.

It is to be noted that whether the Cu metal of the Cu plated layers 26a, 26 b penetrates into the base layers 24 a, 24 b or not can beconfirmed by polishing the side surface (surface LT) of the multilayerceramic capacitor 10 along the length direction L until reaching about ½the dimension in the width direction W, and observing the polishedsurface with an optical microscope.

Furthermore, the metal thicknesses of the external electrodes 22 a, 22 bare about 8.7 μm or more and about 13.9 μm or less. The metal thicknessrefers to a value obtained by measuring the thickness of the metal witha fluorescent X-ray film thickness meter (SFT-9400 from SeikoInstruments Inc.), and converting the measured X-ray Cu amount into afilm thickness.

Furthermore, the plated layers 26 a, 26 b as outermost layers may havesurfaces oxidized. In regard to the area of the oxidation, at leastridges of the external electrodes 22 a, 22 b are preferably oxidized.

This is because with the oxidized plated layers 26 a, 26 b as outermostlayers, when the multilayer ceramic capacitor 10 is embedded into amultilayer printed wiring board, the oxidized film surfaces and a resinof the multilayer printed wiring board are attached through oxygenbinding due to the plated layers 26 a, 26 b oxidized between the platedlayers 26 a, 26 b of the multilayer ceramic capacitor 10 and the resinof the multilayer printed wiring board, and the adhesion is thusimproved between the multilayer ceramic capacitor 10 and the multilayerprinted wiring board. It is to be noted that the effect mentioned aboveis greater when the entire surfaces of the external electrodes 22 a, 22b are oxidized.

In this regard, the arithmetic mean roughness (Ra) at the surfaces ofthe external electrodes 22 a, 22 b is preferably larger than thearithmetic mean roughness (Ra) at the surface of the ceramic body 12.More specifically, the ratio of the arithmetic mean roughness (Ra) atthe surface of the ceramic body 12/the arithmetic mean roughness (Ra) atthe surfaces of the external electrodes 22 a, 22 b preferably fallswithin the range of about 0.06 or more and about 0.97 or less.

In the case of the multilayer ceramic capacitor 10, the arithmetic meanroughness (Ra) at the surfaces of the external electrodes 22 a, 22 b ispreferably larger than the arithmetic mean roughness (Ra) at the surfaceof the ceramic body 12. More specifically, the ratio of the arithmeticmean roughness (Ra) at the surface of the ceramic body 12/the arithmeticmean roughness (Ra) at the surfaces of the external electrodes 22 a, 22b falls within the range of about 0.06 or more and about 0.97 or less.Thus, in close contact between the resin of the multilayer printedwiring board and the multilayer ceramic capacitor 10, the close contactbetween the external electrodes 22 a, 22 b and the resin in theembedding recess for the capacitor, which is provided in the multilayerprinted wiring board, is stronger than the close contact between theceramic body 12 and the resin in the embedding recess for the capacitor,which is provided in the multilayer printed wiring board. Therefore,gaps are more unlikely to be produced between the external electrodes 22a, 22 b and the resin in the embedding recess for the capacitor, whichis provided in the multilayer printed wiring board, and ingress ofmoisture into the gaps is thus also suppressed or prevented. As aresult, reliability of resistance to moisture is ensured for themultilayer ceramic capacitor 10.

In the calculation of the arithmetic mean roughness (Ra) at the surfaceof the ceramic body 12, as a measurement condition, a laser microscope(Product Name: VK-9510) from Keyence Corporation is preferably used at a100-fold lens magnification in a color ultradeep mode set. Themeasurement area with the laser microscope is regarded as a region ofabout 90 μm square including a central portion of the principal surface12 a of the ceramic body 12. Then, the arithmetic mean roughness (Ra) atthe surface of the ceramic body 12 is regarded as a value calculated onthe basis of the surface roughness measured under the measurementcondition.

On the other hand, in the calculation of the arithmetic mean roughness(Ra) at the surfaces of the external electrodes 22 a, 22 b, as ameasurement condition, a laser microscope (Product Name: VK-9510) fromKeyence Corporation is preferably used at a 100-fold lens magnificationin a color ultradeep mode set. The measurement area with the lasermicroscope is regarded as a region of about 90 μm square includingcentral portions of portions of the external electrode 22 a or externalelectrode 22 b provided on the principal surface 12 a or the principalsurface 12 b (principal surface portions 23 a to 23 d).

Then, the arithmetic mean roughness (Ra) at the surfaces of the externalelectrodes 22 a, 22 b is regarded as a value calculated on the basis ofthe surface roughness measured under the measurement condition.

Furthermore, in regard to the principal surface portions 23 a, 23 b ofthe first external electrode 22 a disposed on the principal surfaces 12a, 12 b of the ceramic body 12, as shown in FIG. 5, when the maximumthickness and average thickness of the principal surface portions 23 a,23 b are denoted respectively by D_(max) and D_(ave), the D_(max) andD_(ave) are preferably set so as to satisfy the condition expression ofD_(ave×)250%≧D_(max)≧D_(ave×)120%. Likewise, in regard to the principalsurface portions 23 c, 23 d of the second external electrode 22 bdisposed on the principal surfaces 12 a, 12 b of the ceramic body 12,when the maximum thickness and average thickness of the principalsurface portions 23 c, 23 d are denoted respectively by D_(max) andD_(ave), the D_(max) and D_(ave) are preferably set so as to satisfy thecondition expression of D_(ave×)250%≧D_(max)≧D_(ave×)120%. The adoptionof this structure achieves a more pronounced effect.

When the multilayer ceramic capacitor 10 is formed so that the maximumthicknesses D_(max) and average thicknesses D_(ave) of the principalsurface portions 23 a to 23 d of the external electrodes 22 a, 22 b onthe principal surfaces 12 a, 12 b satisfy the condition expression ofD_(ave×)250%≧D_(max)≧D_(ave×)120%, the principal surface portions 23 ato 23 d are increased in thickness, and principal surface portions 23 ato 23 d function as cushioning materials, and disperse the mounting load(stress) applied in suctioning the multilayer ceramic capacitor 10 witha suction nozzle of a mounting machine (mounter) or pushing thecapacitor into a multilayer printed wiring board.

As a result, the generation of breakages and cracks is significantlyreduced or prevented without concentrating the mounting load (stress) onportions of the multilayer ceramic capacitor 10 with mechanical strengthdecreased.

The maximum thickness D_(max) and the average thickness D_(ave) aremeasured by polishing the side surface of the multilayer ceramiccapacitor 10 along the length direction L until reaching about ½ thedimension in the width direction W, and observing the polished surfacewith an optical microscope.

In addition, when the impurity is potassium, which is present on thesurfaces of the outermost Cu plated layers of the plated layers 26 a, 26b of the external electrodes 22 a, 22 b and the surface of the ceramicbody 12, the multilayer ceramic capacitor 10 is preferably treated sothat the concentration of impurity potassium is about 0.30 ppm or less.Alternatively, when the impurity is sulfur, which is present on thesurfaces of the outermost Cu plated layers of the plated layers 26 a, 26b of the external electrodes 22 a, 22 b and the surface of the ceramicbody 12, the multilayer ceramic capacitor 10 is preferably treated sothat the concentration of impurity sulfur is about 0.40 ppm or less.

Furthermore, FIG. 6 is a schematic drawing for explaining the shape ofthe external electrode 22 a, 22 b of the multilayer ceramic capacitor 10according to a preferred embodiment of the present invention, which isable to achieve a greater effect, and an enlarged view around theexternal electrode 22 a in FIG. 3. It is to be noted that because theexternal electrode 22 b has the same shape as the external electrode 22a, the explanation will not be repeated herein.

The external electrode 22 a of the multilayer ceramic capacitor 10according to this preferred embodiment is preferably formed so that whenthe distance from the position of the maximum thickness on the principalsurface 12 a of the ceramic body 12 to the position of the maximumthickness on the end surface 12 e of the ceramic body 12 is referred toas a dimension Ed, whereas the distance from the position of the maximumthickness on the end surface 12 e of the ceramic body 12 to an edge endof the external electrode 22 a on the principal surface 12 a of theceramic body 12 is referred to as a dimension e, the ratio Ed/e is about0.243 or more and about 0.757 or less. The adoption of this structureachieves a more pronounced effect.

More specifically, in the case of the multilayer ceramic capacitor 10,the external electrodes 22 a, 22 b are preferably formed so that whenthe distance from the position of the maximum thickness on the principalsurface 12 a of the ceramic body 12 to the position of the maximumthickness on the end surface 12 e of the ceramic body 12 is referred toas a dimension Ed, whereas the distance from the position of the maximumthickness on the end surface 12 e of the ceramic body 12 to an edge endof the external electrode 22 a on the principal surface 12 a of theceramic body 12 is referred to as a dimension e, the ratio Ed/e is about0.243 or more and about 0.757 or less. Thus, the stress concentrationwhich is generated at corners of the multilayer ceramic capacitor 10 issignificantly reduced or prevented. As a result, it becomes possible tosuppress or prevent peeling that is generated between the corners of themultilayer ceramic capacitor 10 and the resin in the embedding recessfor the capacitor, which is provided in the multilayer printed wiringboard.

The dimension Ed and the dimension e are measured by polishing, for across section, the side surface of the multilayer ceramic capacitor 10along the length direction L until reaching about ½ the dimension in thewidth direction W, and observing the polished surface with an opticalmicroscope.

Furthermore, FIG. 7 shows a cross-sectional view of a preferredembodiment of a multilayer ceramic capacitor according to the presentinvention, which is able to achieve a greater effect, along the lineIII-III of FIG. 1.

The height of an effective portion that is a portion of the ceramic body12 where the first internal electrodes 16 a and the second internalelectrode 16 b are provided is referred to as A in the height directionT. The height of the ceramic layer 14 for outer layer that is a portionof the ceramic body 12 located closer to the principal surface 12 a thanthe effective portion is referred to as B in the height direction T. Theheight of the ceramic layer 14 for outer layer that is a portion of theceramic body 12 located closer to the principal surface 12 d than theeffective portion is referred to as C in the height direction T. In thiscase, the ratios A/B and A/C each preferably falls within the range ofabout 0.5 to about 16.

Furthermore, in regard to the multilayer ceramic capacitor 10, when thedimension in the height direction T is about 50 μm to about 150 μm, theratios of A/B and A/C each preferably fall within the range of about 0.6to about 6.

In addition, in regard to the multilayer ceramic capacitor 10, when thedimension in the height direction T is about 150 μm to about 250 μm, theratios of A/B and A/C each preferably fall within the range of about 2to about 16.

As just described, in regard to the multilayer ceramic capacitor 10,when the ratios of A/B and A/C each fall within the range of about 0.5to about 16, the crack generation in the ceramic body 12 which startsfrom the contact point between the principal surface 12 a of the ceramicbody 12 and the end of the external electrode 22 a is effectivelysuppressed or prevented. As the reason therefor, the following reason isconsidered.

In the multilayer ceramic capacitor 10, the ratios A/B and A/C eachfalls within the range of about 0.5 to about 16, thus leading to thesmall height ratio of the ceramic layers 14 for outer layers closer tothe principal surface 12 a and the principal surface 12 b to theeffective portion Eep. More specifically, the ceramic layers 14 forouter layers closer to the principal surface 12 a and the principalsurface 12 b are relatively small in height. For this reason, when theceramic body 12 is subjected to firing, compressive stress applied tothe ceramic layers 14 for outer layers closer to the principal surface12 a and the principal surface 12 b is likely to be increased, due tocontraction of electrode paste layers defining the internal electrodes16 a, 16 b. For this reason, for example, in the case of baking theexternal electrodes 22 a, 22 b after firing the ceramic body 12, thecompressive stress of the ceramic layers 14 for outer layers closer tothe principal surface 12 a and the principal surface 12 b can beincreased before baking the external electrodes 22 a, 22 b. For thisreason, tensile stress is less likely to be applied to the ceramic body12, even when the electrode paste layers defining the externalelectrodes 22 a, 22 b are contracted in baking the external electrodes22 a, 22 b. Therefore, the ceramic body 12 is less likely to be cracked.Even in the case of simultaneously carrying out firing for the ceramicbody 12 and firing defining the external electrodes 22 a, 22 b, tensilestress is less likely to be applied to the ceramic body 12 for the samereason, and thus is less likely to be applied to the ceramic body 12.

From the perspective of effectively suppressing or preventing the crackgeneration in the ceramic body 12, when the dimension of the multilayerceramic capacitor 10 in the height direction T is about 50 μm to about150 μm, the ratios of A/B and A/C each preferably fall within the rangeof about 0.6 to about 6.

When the dimension of the multilayer ceramic capacitor 10 in the heightdirection T is about 150 μm to about 250 μm, the ratios of A/B and A/Ceach preferably fall within the range of about 2 to about 16.

It is to be noted that A, B, and C can be measured in the followingmanner. More specifically, a cross section is exposed by polishing theside surface 12 c of the multilayer ceramic capacitor 10 until thedimension in the width direction W is reduced down to about ½. A, B, andC can be measured at the center of the cross section in the lengthdirection with the use of an optical microscope. The height A can bemeasured at a portion located in the center of the cross section in thelength direction and in the center thereof in the height direction T.

Furthermore, FIG. 8 shows a cross-sectional view of a preferredembodiment of a multilayer ceramic capacitor according to the presentinvention, which is able to achieve a greater effect, along the lineIII-III of FIG. 1.

More specifically, in the multilayer ceramic capacitor 10, when thedimension in the length direction L of the multilayer ceramic capacitor10 is referred to as L0, whereas the distance in the length direction Lis referred to as L1 between an end in the length direction L of aportion of the first external electrode 22 a located on the principalsurface 12 a and an end of the second internal electrode 16 b closer tothe end surface 12 e, the ratio of L1/L0 is preferably about 0.05 toabout 0.35. Accordingly, the ceramic body 12 is unlikely to be crackedin the multilayer ceramic capacitor 10. The ratio of L1/L0 is morepreferably about 0.13 or more.

Further, in regard to L0, a cross section is exposed by polishing theside surface 12 c, 12 d of the multilayer ceramic capacitor 10 until thedimension in the width direction W is reduced down to about ½. The crosssection can be observed with the use of an optical microscope to make adimension measurement.

In regard to L1, a cross section is exposed by polishing the sidesurface 12 c, 12 d of the multilayer ceramic capacitor 10 until thedimension in the width direction W is reduced down to about ½. The crosssection is observed with the use of an optical microscope to firstspecify the second internal electrode 16 b closest to the end surface 12e. Then, the dimension can be obtained by measuring the distance in thelength direction L between the second internal electrode 16 b and theend surface 12 e.

In addition, in this regard, the length of the first external electrode22 a in the length direction L is referred to as LE1 as viewed from theprincipal surface 12 b. The length of the first external electrode 22 ain the length direction L is referred to as LE2 as viewed from theprincipal surface 12 a. The length of the second external electrode 22 bin the length direction L is referred to as LE3 as viewed from theprincipal surface 12 b. The length of the second external electrode 22 bin the length direction L is referred to as LE4 as viewed from theprincipal surface 12 a. The distance in the length direction L isreferred to as LE5 between the thickest portion of the first externalelectrode 22 a located on the principal surface 12 b and the outermostend of the first external electrode 22 a in the length direction L. Thedistance in the length direction L is referred to as LE6 between thethickest portion of the first external electrode 22 a located on theprincipal surface 12 a and the outermost end of the first externalelectrode 22 a in the length direction L. The distance in the lengthdirection L is referred to as LE7 between the thickest portion of thesecond external electrode 22 b located on the principal surface 12 b andthe outermost end of the second external electrode 22 b in the lengthdirection L. The distance in the length direction L is referred to asLE8 between the thickest portion of the second external electrode 22 blocated on the principal surface 12 a and the outermost end of thesecond external electrode 22 b in the length direction L. The ratio ofthe absolute value of the difference between LE5 and LE6 to the longerone of LE1 and LE2 ((absolute value of difference between LE5 andLE6)/(longer one of LE1 and LE2)) is referred to as A1. The ratio of theabsolute value of the difference between LE7 and LE8 to the longer oneof LE3 and LE4 ((absolute value of difference between LE7 andLE8)/(longer one of LE3 and LE4)) is referred to as A2.

In this case, in the multilayer ceramic capacitor 10, A1 and A2 are eachpreferably about 0.2 or more. Thus, the ceramic body 10 is more unlikelyto be cracked in mounting the multilayer ceramic capacitor 10 onto amounting substrate with the use of a mounter.

Further, in regard to LE1 and LE3, a cross section is exposed bypolishing the side surface 12 c, 12 d of the multilayer ceramiccapacitor 10 until the dimension in the width direction W is reduceddown to about ½. The dimensions can be obtained by observing the crosssection of the multilayer ceramic capacitor from the principal surface12 b with the use of an optical microscope, and measuring the length ofthe external electrode in the center in the width direction W.

In addition, in regard to LE2 and LE4, a cross section is exposed bypolishing the side surface 12 c, 12 d of the multilayer ceramiccapacitor 10 until the dimension in the width direction W is reduceddown to about ½. The dimensions can be obtained by observing the crosssection of the multilayer ceramic capacitor 10 from the principalsurface 12 a with the use of an optical microscope, and measuring thelength of the external electrode in the center in the width direction W.

In addition, in regard to LE5 to LE8, a cross section is first exposedby polishing the side surface 12 c, 12 d of the multilayer ceramiccapacitor 10 until the dimension in the width direction W is reduceddown to about ½. This cross section is observed with the use of anoptical microscope to specify the thickest portion of the externalelectrode located on the principal surface. Next, the dimensions can beobtained by measuring the distance between the thickest portion and theoutermost end of the external electrode.

FIG. 9 shows a cross-sectional view of a preferred embodiment of amultilayer ceramic capacitor according to the present invention, whichis able to achieve a greater effect, along the line III-III of FIG. 1.

In this regard, in the multilayer ceramic capacitor 10, the dimensionsa, b, c, d, e, and f shown in FIG. 9 are defined as follows: “a” is adistance in the height direction between the principal surface 12 a andan effective portion E that refers to a region where the first internalelectrodes 16 a and the second internal electrodes 16 b are opposed inthe height direction T; “b” is a distance in the length directionbetween the end surface 12 e and the effective portion Eep in the lengthdirection L; “c” is a thickness of the thickest portion of the baselayer 24 a provided over the principal surface 12 a; “d” is a distancein the length direction L between a point of the base layer 24 a overthe end surface 12 e which is farthest from the end surface 12 e and anend of the base layer 24 a over the principal surface 12 a which isclosest to the end surface 12 f; “e” is a thickness of the thickestportion of the base layer 24 a provided over the end surface 12 e; and“f” is a height of the ceramic body 12.

In the multilayer ceramic capacitor 10, the ratio (c·d+e·f/2)/(a·b) ispreferably about 6 or less. For this reason, with a large (a·b), theridges of the ceramic body 12 are increased in strength. In addition,the tensile stress applied to the ridges of the ceramic body 12 is lowbecause the base layer 24 a is thin with a small (c·d+e·f/2). Therefore,the multilayer ceramic capacitor 10 is unlikely to be cracked from theridges of the ceramic body 12.

Furthermore, the ratio (c·d+e·f/2)/(a·b) is preferably about 2 or more.Thus, the base layer 24 a can be made not to be excessively thin.Accordingly, the multilayer ceramic capacitor 10 has excellentresistance to moisture.

Further, the thicknesses of the base layers 24 a, 24 b can be measuredthrough the observation of, with a microscope, a cross section exposedby polishing the side surface 12 c or side surface 12 d of themultilayer ceramic capacitor 10 until the height of the multilayerceramic capacitor 10 is reduced to about ½.

The distance a in the height direction between the effective portion Eepwhere the first internal electrodes 16 a and the second internalelectrodes 16 b are opposed in the height direction T, and the principalsurface 12 a can be measured through the observation of, with amicroscope, a cross section exposed by polishing the side surface 12 cor side surface 12 d of the multilayer ceramic capacitor 10 until theheight of the multilayer ceramic capacitor 10 is reduced to about ½.

In the length direction L, the distance b in the length directionbetween the end surface 12 e and the effective portion Eep is regardedas the distance between the second internal electrode 16 b extendingclosest to the end surface 12 e among the second internal electrodes 16b and the end surface 12 e in a cross section exposed by polishing theside surface 12 c or side surface 12 d of the multilayer ceramiccapacitor 10 until the height of the multilayer ceramic capacitor 10 isreduced to about ½.

The height f of the ceramic body 12 can be obtained by measuring theheight of the center in the width direction W in a cross section exposedby polishing the end surface 12 e or end surface 12 f of the ceramicbody 12 until the height of the ceramic body 12 in the length directionL is reduced to about ½.

Furthermore, FIG. 10 shows a cross-sectional view of a preferredembodiment of a multilayer ceramic capacitor according to the presentinvention, which is able to achieve a greater effect, along the lineIII-III of FIG. 1. The multilayer ceramic capacitor 10 according to thepresent invention is achieved by meeting any of the conditions (1) to(5) listed below.

Condition 1

The internal electrode located closest to the principal surface 12 a isconfigured so that the multilayer ceramic capacitor 10 is about 0.9 mmor more and about 1.1 mm or less in dimension in the length direction L,the multilayer ceramic capacitor 10 is about 0.4 mm or more and about0.6 mm or less in dimension in the width direction W, the multilayerceramic capacitor 10 is about 0.085 mm or more and about 0.11 mm or lessin dimension in the height direction T, and the ratio(T_(MAX)−T_(MIN))/T of about 1.0% to about 5.0% is met. The targetdimensions of the multilayer ceramic capacitor 10 preferably are about1.0 mm in dimension in the length direction L, about 0.5 mm in dimensionin the width direction W, and about 0.10 mm in dimension in the heightdirection T.

Condition 2

The internal electrode located closest to the principal surface 12 a isconfigured so that the multilayer ceramic capacitor 10 is about 0.9 mmor more and about 1.1 mm or less in dimension in the length direction L,the multilayer ceramic capacitor 10 is about 0.4 mm or more and about0.6 mm or less in dimension in the width direction W, the multilayerceramic capacitor 10 is about 0.12 mm or more and about 0.15 mm or lessin dimension in the height direction T, and the ratio(T_(MAX)−T_(MIN))/T of about 1.3% to about 5.3% is met. The targetdimensions of the multilayer ceramic capacitor 10 preferably are about1.0 mm in dimension in the length direction L, about 0.5 mm in dimensionin the width direction W, and about 0.15 mm in dimension in the heightdirection T.

Condition 3

The internal electrode located closest to the principal surface 12 a isconfigured so that the multilayer ceramic capacitor 10 is about 0.9 mmor more and about 1.1 mm or less in dimension in the length direction L,the multilayer ceramic capacitor 10 is about 0.4 mm or more and about0.6 mm or less in dimension in the width direction W, the multilayerceramic capacitor 10 is about 0.18 mm or more and about 0.20 mm or lessin dimension in the height direction T, and the ratio(T_(MAX)−T_(MIN))/T of about 1.5% to about 5.0% is met (the targetdimensions of the multilayer ceramic capacitor 10 are about 1.0 mm indimension in the length direction L, about 0.5 mm in dimension in thewidth direction W, and about 0.20 mm in dimension in the heightdirection T.

Condition 4

The internal electrode located closest to the principal surface 12 a isconfigured so that the multilayer ceramic capacitor 10 is about 0.9 mmor more and about 1.1 mm or less in dimension in the length direction L,the multilayer ceramic capacitor 10 is about 0.4 mm or more and about0.6 mm or less in dimension in the width direction W, the multilayerceramic capacitor 10 is about 0.21 mm or more and about 0.23 mm or lessin dimension in the height direction T, and the ratio(T_(MAX)−T_(MIN))/T of about 1.8% to about 5.9% is met. The targetdimensions of the multilayer ceramic capacitor 10 preferably are about1.0 mm in dimension in the length direction L, about 0.5 mm in dimensionin the width direction W, and about 0.22 mm in dimension in the heightdirection T.

Condition 5

The internal electrode located closest to the principal surface 12 a isconfigured so that the multilayer ceramic capacitor 10 is about 0.9 mmor more and about 1.1 mm or less in dimension in the length direction L,the multilayer ceramic capacitor 10 is about 0.4 mm or more and about0.6 mm or less in dimension in the width direction W, the multilayerceramic capacitor 10 is about 0.24 mm or more and about 0.30 mm or lessin dimension in the height direction T, and the ratio(T_(MAX)−T_(MIN))/T of about 1.2% to about 6.0% is met. The targetdimensions of the multilayer ceramic capacitor 10 preferably are about1.0 mm in dimension in the length direction L, about 0.5 mm in dimensionin the width direction W, and about 0.25 mm in dimension in the heightdirection T.

This multilayer ceramic capacitor 10 preferably meets any of theconditions (1) to (5). Thus, the ceramic body 12 is reinforced in apreferred manner with the first internal electrodes 16 a and the secondinternal electrodes 16 b, and the stress applied to the ceramic body 12when the multilayer ceramic capacitor 10 is mounted with the use of amounter is dispersed. Accordingly, the ceramic body 12 is more unlikelyto be cracked in mounting the multilayer ceramic capacitor 10. Becausecracks are unlikely to be generated, the generation of short circuitdefects in the multilayer ceramic capacitor 10 is also effectivelysuppressed or prevented.

It is to be noted that T, T_(MAX), and T_(MIN) can be each measured byobserving, with the use of a microscope, a cross section exposed bypolishing the end surface 12 e or end surface 12 f of the multilayerceramic capacitor 10 until the dimension in the length direction L isreduced down to about ½.

Furthermore, FIG. 11 shows a cross-sectional view of a preferredembodiment of a multilayer ceramic capacitor according to the presentinvention, which is able to achieve a greater effect, along the lineIII-III of FIG. 1.

Multilayer ceramic capacitors preferably have external electrodes thatare unlikely to be peeled from ceramic bodies. In the multilayer ceramiccapacitor 10, reactive layers 28 containing about 5 atomic % to about 15atomic % of Ti, about 5 atomic % to about 15 atomic % of Si, and about 2atomic % to about 10 atomic % of V are preferably provided between theceramic body 12 and the base layers 24 a, 24 b. Thus, in the multilayerceramic capacitor 10, the external electrodes 22 a, 22 b are unlikely tobe peeled from the ceramic body 12.

It is to be noted that as a cause of the fact that the externalelectrodes are unlikely to be peeled, for example, it is conceivablethat when the ceramic body with the base layers formed is immersed in aplating bath in order to form plated layers, glass in the base layers iseluted to decrease the adhesion strength between the base layers and theceramic body. The reactive layers 28 containing about 5 atomic % toabout 15 atomic % of Ti, about 5 atomic % to about 15 atomic % of Si,and about 2 atomic % to about 10 atomic % of V are preferably formedbetween the ceramic body 12 and the base layers 24 a, 24 b. The reactivelayer 28 which has this composition is formed in such a way that theceramic body 12 is reacted with a base paste in firing the ceramic body12. The reactive layers 28 have low solubility in plating baths such asa sulfuric acid Cu bath, a pyrophosphoric acid Cu bath, and a cyanide Cubath. For this reason, the adhesion strength between the base layers 24a, 24 a and the ceramic body 12 is unlikely to be decreased in the caseof forming the plated layers 26 a, 26 b by Cu plating. Accordingly, theexternal electrodes 22 a, 22 b are unlikely to be peeled on the ceramicbody 12.

In addition, from the perspective of effective suppression or preventionof peeling of the external electrodes 22 a, 22 b, the maximum thicknessof the reactive layer 28 is preferably about 0.5 μm to about 5 μm. Theexternal electrodes is peeled from the ceramic body when the maximumthickness of the reactive layer 28 is smaller than about 0.5 μm, whereasthe deflective strength is decreased because of a decrease in thestrength itself of the ceramic body 12 when the maximum thickness of thereactive layer 28 is larger than about 5 μm.

Furthermore, FIG. 12 shows a cross-sectional view of a preferredembodiment of a multilayer ceramic capacitor according to the presentinvention, which is able to achieve a greater effect, along the lineIII-III of FIG. 1.

In this case, in the multilayer ceramic capacitor 10, the thickness ofthe thickest portion of the first external electrode 22 a located on theend surface 12 e is referred to as t1 in a cross section passing throughthe center in the width direction W and extending in the lengthdirection L and the height direction T.

In addition, in the multilayer ceramic capacitor 10, the thickness ofthe thickest portion of the first external electrode 22 a located on theprincipal surface 12 a is referred to as t2 in a cross section passingthrough the center in the width direction W and extending in the lengthdirection L and the height direction T.

Furthermore, in the multilayer ceramic capacitor 10, the thickness ofthe first external electrode 22 a on a line passing through the point ofintersection between a tangent line on a corner of the ceramic body 12and the corner and the point of intersection between a line along theprincipal surface 12 a and a line along the end surface 12 e is referredto as t3 in a cross section passing through the center in the widthdirection W and extending in the length direction L and the heightdirection T.

The multilayer ceramic capacitor 10 preferably is embedded into amultilayer printed wiring board, and used. In such a case, themultilayer ceramic capacitor 10 preferably has excellent resistance tomoisture, and excellent adhesion to the resin constituting themultilayer printed wiring board.

As a result of earnest study, it has been found that the shape of theexternal electrode is related to the moisture resistance of themultilayer ceramic capacitor 10 and the adhesion thereof to the resin.Specifically, the relationships among t1 to t3 can control the moistureresistance and the adhesion to the resin.

More specifically, in the multilayer ceramic capacitor 10, the ratiot2/t1 is preferably about 0.7 to about 1.0, and the ratio t3/t1 ispreferably about 0.4 to about 1.2. Thus, the multilayer ceramiccapacitor 10 has excellent resistance to moisture, and excellentadhesion to the resin of the multilayer printed wiring board.

An excessively small ratio t2/t1 may result in failure to sufficientlyensure the thicknesses of the external electrodes around corners of theceramic body, and ingress of plating solutions, etc., into themultilayer ceramic capacitor 10, thus decreasing reliability ofresistance to moisture. On the other hand, an excessively large ratiot2/t1 may eliminate the roundness of the external electrodes aroundcorners of the ceramic body, and make stress more likely to beconcentrated on the corners, thus decreasing the adhesion between themultilayer ceramic capacitor 10 and the resin of the multilayer printedwiring board.

An excessively small ratio t3/t1 may result in failure to sufficientlyensure the thicknesses of the external electrodes, and ingress ofplating solutions, etc., into the multilayer ceramic capacitor 10, thusdecreasing the moisture resistance. On the other hand, an excessivelylarge ratio t3/t1 may eliminate the roundness of the external electrodesaround corners of the ceramic body, and make stress more likely to beconcentrated on the corners, thus decreasing the adhesion between themultilayer ceramic capacitor 10 and the resin of the multilayer printedwiring board.

It is to be noted that t1 to t3 can be measured in the following manner.

Method of T1 Measurement

A cross section is exposed by polishing the side surface 12 c or sidesurface 12 d of the multilayer ceramic capacitor 10 until the height ofthe multilayer ceramic capacitor 10 in the width direction W is reduceddown to about ½. The thickness t1 of the thickest portion of the firstexternal electrode 22 a located on the end surface 12 e can be measuredby observing the cross section with the use of a microscope.

Method of T2 Measurement

A cross section is exposed by polishing the side surface 12 c or sidesurface 12 d of the multilayer ceramic capacitor 10 until the height ofthe multilayer ceramic capacitor 10 in the width direction W is reduceddown to about ½. The thickness t2 of the thickest portion of the firstexternal electrode 22 a located on the principal surface 12 a can bemeasured by observing the cross section with the use of a microscope.

Method of T3 Measurement

A cross section is exposed by polishing the side surface 12 c or sidesurface 12 d of the multilayer ceramic capacitor 10 until the height ofthe multilayer ceramic capacitor 10 in the width direction W is reduceddown to about ½. The thickness t3 of the first external electrode 22 aon the line passing through the point of intersection between thetangent line on the corner of the ceramic body 12 and the corner and thepoint of intersection between the line along the principal surface 12 aand the line along the end surface 12 e can be measured by observing thecross section with the use of a microscope.

It is to be noted that, although not shown, the first external electrode22 a and the second external electrode 22 b, or respective portions ofthe first external electrode 22 a and second external electrode 22 b(more specifically, respective portions of the base layer 24 a and baselayer 24 b) may be embedded in the ceramic body 12. In this case, whenthe thicknesses of central portions of the principal surface portions 23a, 23 b of the external electrode 22 a on the principal surfaces 12 a,12 b are referred to as t0, whereas the maximum thickness of the portionof the external electrode 22 a embedded in the ceramic body 12 isreferred to as t1, the condition of ( 1/10)t0≦t1≦(⅖)t0 is preferablymet. Likewise, when the thicknesses of central portions of the principalsurface portions 23 c, 23 d of the external electrode 22 b on theprincipal surfaces 12 a, 12 b are referred to as t0, whereas the maximumthickness of the portion of the external electrode 22 b embedded in theceramic body 12 is referred to as t1, the condition of about (1/10)t0≦t1≦about (⅖)t0 is preferably met.

When t1 is less than about ( 1/10)t0, the adhesion between the externalelectrodes 22 a, 22 b and the ceramic body 12 may be excessivelydecreased to make the external electrodes 22 a, 22 b more likely to bepeeled, thus decreasing the reliability of the multilayer ceramiccapacitor 10. In addition, when t1 is less than about ( 1/10)t0, theportions of the external electrodes 22 a, 22 b, which are not embedded,may be excessively increased in height to sufficiently reduce themultilayer ceramic capacitor 10 in height.

On the other hand, when t1 is greater than about (⅖)t0, the reliabilityof the multilayer ceramic capacitor 10 may be decreased. Morespecifically, there is a possibility that high stress will be applied tothe internal electrode 16 a or the internal electrode 16 b to damage theinternal electrode 16 a or the internal electrode 16 b, when theexternal electrodes 22 a, 22 b are embedded in the principal surfaces 12a, 12 b of the ceramic body 12. As a result, desired capacitance isunable to be obtained, or short circuit may be caused.

As a method for measuring the embedded amounts (t0 and t1), the sidesurface 12 c, 12 d of the multilayer ceramic capacitor 10 can bepolished for a cross section along the length direction L down to about½ the dimension in the width direction W, and the thicknesses of thecentral portions of the external electrodes 22 a, 22 b at the points inthe cross section can be measured with an optical microscope or thelike.

In addition, edge ends of the external electrodes 22 a, 22 b located onthe principal surfaces 12 a, 12 b of the ceramic body 12 preferably havelinear shapes in planar view (that is, preferably not crescent shapes).As shown in FIGS. 13A and 13B, the linear shape refers to, when the lineconnecting both ends at end edges of the external electrodes 22 a, 22 bformed on the principal surfaces 12 a, 12 b is regarded as a referenceline P in planar view, a shape where the width h with respect to thereference line P is not more than about ±30 μm away from the positionsof the centers in the width direction W (the positions at about ½dimensions in the width direction W) of the end edges of the externalelectrodes 22 a, 22 b. Thus, the external electrodes 22 a, 22 b are ableto be uniformly formed even on both ends of the ceramic body 12 in thewidth direction W. As a result, even when the laser for irradiation issomewhat shifted in embedding the multilayer ceramic capacitor 10 into amultilayer printed wiring board, it is possible to irradiate thesurfaces of the external electrodes 22 a, 22 b with the laser, and theprobability of joint between the via hole and the multilayer ceramiccapacitor 10 is increased.

The dimensions of the multilayer ceramic capacitor 10 are preferablyabout 0.9 mm or more and about 1.1 mm or less in the length direction L,about 0.4 mm or more and about 0.6 mm or less in the width direction W,and about 0.085 mm or more and about 0.15 mm or less in the heightdirection T.

In the multilayer ceramic capacitor 10, the Cu metal of the Cu platedlayers 26 a, 26 b penetrates in the base layers 24 a, 24 b to a positionof about ⅓ or more of the thicknesses of the base layers 24 a, 24 b fromthe surface layers of the base layers 24 a, 24 b, and the Cu contentrate is thus high in the base layers 24 a, 24 b. Accordingly, incombination with the base layers 24 a, 24 b and Cu plated layers 26 a,26 b in total, the content rate of Cu per unit thickness is increased toimprove the thermal conductivity (heat release performance) of the baselayers 24 a, 24 b, and increase the laser resistance of the externalelectrodes 22 a, 22 b.

In addition, in the multilayer ceramic capacitor 10, the Cu metal of theCu plated layers 26 a, 26 b penetrates in the base layers 24 a, 24 b toa position of about ⅓ or more of the thicknesses of the base layers 24a, 24 b from the surface layers of the base layers 24 a, 24 b. Thus, thedifference in level between the surface of the multilayer printed wiringboard and the surfaces of the external electrodes 22 a, 22 b are reducedbecause the external electrode 22 a (22 b) including the base layer 24 a(24 b) and the Cu plated layer 26 a (26 b) is reduced in totalthickness. As a result, the gap between the surface of the multilayerprinted wiring board and the mounting surface 12 a (or 12 b) of theceramic body 12 is narrowed to make peeling less likely to be causedbetween the multilayer printed wiring board and the external electrodes22 a, 22 b, and also improve the mechanical strength of the component.

Next, a non-limiting example of a method for producing the previouslydescribed multilayer ceramic capacitor 10 will be described. FIG. 14 isa flowchart showing a method for manufacturing the multilayer ceramiccapacitor 10.

In a step S1, slurry for sheet forming is prepared in such a way that anorganic binder, a dispersant, and a plasticizer, etc. are added to aceramic powder containing a barium titanate material, a strontiumtitanate material, or the like. Next, the slurry for sheet forming isformed into ceramic green sheets for inner layers or outer layers by adoctor blade method.

Next, in a step S2, an internal electrode paste containing Ag is appliedonto the ceramic green sheets for inner layers by a screen printingmethod, thus forming electrode paste films to define and function as thefirst internal electrodes 16 a and the second internal electrodes 16 b.

Next, in a step S3, the plurality of ceramic green sheets for innerlayers, which have the electrode paste films formed, are stacked so asto alternate the electrode paste films for the first internal electrodes16 a and the electrode paste films for the second internal electrodes 16b. Furthermore, the plurality of ceramic green sheets for outer layerswithout any electrode paste films formed for internal electrodes arestacked so as to sandwich the stacked ceramic green sheets for innerlayers, and pressed by pressure bonding to prepare a mother laminatedbody.

In this regard, as for the mold for use in the press, the mold isprovided with appropriate surface roughness to obtain the ceramic body12 with desired arithmetic mean roughness (Ra). It is to be noted thatthe surface of the ceramic body 12 may be subjected to a physical impact(for example, polishing) or chemical treatment (for example, acidetching), as a method for providing the surface of the ceramic body 12with desired arithmetic mean roughness (Ra).

Then, this mother laminated body is cut along a virtual cut line on themother laminated body with a dicing machine or a pushing machine into asize for individual ceramic bodies 12 to provide a plurality of unfiredceramic bodies 12 (raw ceramic laminated bodies).

The unfired ceramic bodies 12 have ridges and corners shaped in R bybarrel polishing.

Next, in a step S4, the unfired ceramic bodies 12 are subjected tobinder removal treatment, and then firing to provide sintered ceramicbodies 12. The firing temperature can be set appropriately depending onthe types of the ceramic material and conductive paste used. The firingtemperature can be, for example, about 900° C. or higher and about 1300°C. or lower. The ceramic green sheets for inner layers and outer layersand the electrode paste films are subjected to co-firing to turn theceramic green sheets for inner layers into the ceramic layers 14 forinner layers, turn the ceramic green sheets for outer layers into theceramic layers 14 for outer layers, and turn the electrode paste filmsinto the first internal electrodes 16 a or the second internalelectrodes 16 b.

Next, in a step S5, a base paste (a paste containing Cu and glass) forthe external electrodes 22 a, 22 b is applied by a method such asdipping to both ends of the sintered ceramic body 12. The base pasteapplied to the ceramic body 12 is subjected to hot-air drying for about10 minutes in the range of about 60° C. or higher and about 180° C. orlower, for example.

Next, in a step S6, the base paste applied to the ceramic body 12 isbaked.

Thus, the base layers 24 a, 24 b of the external electrodes 22 a, 22 bare formed. The baking temperature is preferably adjusted to, forexample, about 780° C. or higher and about 900° C. or lower.

Next, in a step S7, plated layers are formed on the surfaces of the baselayers 24 a, 24 b to form the external electrodes 22 a, 22 b.Thereafter, if necessary, through immersion in a roughening liquid, theexternal electrodes 22 a, 22 b are obtained which have desiredarithmetic mean roughness (Ra) at the surfaces of the externalelectrodes 22 a, 22 b. It is to be noted that the surfaces of theexternal electrodes 22 a, 22 b may be subjected to a physical impact(for example, polishing), as a method for providing the surfaces of theexternal electrodes 22 a, 22 b with desired arithmetic mean roughness(Ra). Then, the formation is achieved so that the ratio of thearithmetic mean roughness (Ra) at the surface of the ceramic body/thearithmetic mean roughness at the surface of the external electrode fallswithin the range of about 0.06 or more and about 0.97 or less.

Next, if necessary, in a step S8, a cleaning process is applied to themultilayer ceramic capacitor 10 in order to obtain the multilayerceramic capacitor 10 with small impurity amounts (contamination amounts)of K (potassium) and S (sulfur). Pure water or an extremely lowconcentration of sulfuric acid or hydrochloric acid is used for thecleaning liquid. For cleaning the multilayer ceramic capacitor 10,various methods are selected depending on the size, shape, amount ofthroughput, etc, for products. For example, the capacitor is stirred ina cleaning tank, or cleaned by a batch process. Alternatively, thecapacitor is subjected to shower cleaning with a cleaning liquid whilebeing transferred, or subjected to ultrasonic cleaning. In this way, themultilayer ceramic capacitor 10 is obtained which has small impurityamounts (contamination amounts) of K (potassium) and S (sulfur).

It is to be noted that in the step S5, in the case of applying the basepaste by dipping, the position of the maximum thickness of the basepaste formed on the principal surfaces 12 a, 12 b of the ceramic body 12can be varied by adjusting the rheology of the base paste, carrying outsurface treatment of the ceramic body, and applying the base pastetwice, if necessary. In this way, the external electrodes 22 a, 22 b canbe formed so that the ratio Ed/e between the dimensions Ed and e for theexternal electrodes 22 a, 22 b falls within the range of about0.243≦E/e≦about 0.757.

In addition, the multilayer ceramic capacitor 10 which is able toachieve a greater effect, as shown in FIG. 7, can be obtained by, in thestep S3, for control, changing the stacked number of ceramic greensheets for inner layers or ceramic green sheets for outer layers, andappropriately changing the height A of the effective portion, the heightB of the ceramic layer for an outer layer closer to the principalsurface 12 a, and the height C of the ceramic layer for an outer layercloser to the principal surface 12 b.

In addition, the multilayer ceramic capacitor 10 which is able toachieve a greater effect, as shown in FIG. 8, can be obtained by, in thestep S5, appropriately controlling the lengths in the length direction Lof the portions of the external electrodes located on the principalsurfaces in accordance with the following method. More specifically, thelengths in the length direction of the portions of the externalelectrodes located on the principal surfaces can be controlled by, forexample, varying the wettability of the ceramic body to the conductivepaste. The wettability of the ceramic body to the base paste can bevaried by, for example, applying a surfactant, or carrying out plasmatreatment or the like.

Furthermore, the multilayer ceramic capacitor 10 which is able toachieve a greater effect, as shown in FIG. 9, can be obtained in such away that the distance a in the height direction T between the effectiveportion Eep where the first internal electrodes 16 a and the secondinternal electrodes 16 b are opposed in the height direction T and theprincipal surface 12 a is varied appropriately by increasing ordecreasing the stacked number of ceramic green sheets for outer layersin the step S3.

In addition, in the step S2, the distance b in the length directionbetween the end surface 12 e and the effective portion Eep can becontrolled in the length direction L by appropriately changing the sizeof the electrode figure of a printing plate to form the internalelectrodes on the ceramic green sheets for inner layers.

Furthermore, the height f of the ceramic body 12 can be arbitrarilyvaried depending on the combination of the height of the ceramic greensheets for inner layers with the internal electrodes formed or theceramic green sheets for outer layers, that is, the effective layers,with the ceramic layers 14 for outer layers in the step S3.

Further, for the multilayer ceramic capacitor 10 which is able toachieve a greater effect, as shown in FIG. 9, the thickness c of theportion of the base layer 24 a provided over the principal surface 12 ais able to be adjusted depending on the combination of the viscosity ofthe base paste in which the ceramic body 12 is immersed for dipping, thepaste thickness in the paste bath, the pull-up rate after the immersionof the ceramic body 12 in the step S5.

In addition, in the step S5, the distance d in the length direction Lbetween the thickest portion of the base layer 24 a provided over theend surface 12 e and a portion of the base layer 24 a located closest tothe end surface 12 f, which is located over the principal surface 12 ais able to be controlled with the viscosity of the base paste in whichthe ceramic body 12 is immersed for dipping, the paste thickness in thepaste bath, and the period of time for which the ceramic body 12 isimmersed in the paste.

Furthermore, in the step S5, the thickness e of the portion of the baselayer 24 a provided over the end surface 12 e is able to be adjusteddepending on the combination of the viscosity of the base paste in whichthe ceramic body 12 is immersed for dipping, the paste thickness in thepaste bath, the pull-up rate after the immersion of the ceramic body 12.In addition, depending on the condition for the pull-up, it is possibleto change the magnitude relationship with the thickness of the portionof the base layer 24 a provided over the principal surface 12 a.

In addition, the multilayer ceramic capacitor 10 which is able toachieve a greater effect, as shown in FIG. 10, can be obtained in such away that a ceramic green sheet for an outer layer, ceramic green sheetsfor inner layers with electrode paste films formed in shapescorresponding to the first internal electrodes 16 a or the secondinternal electrodes 16 b, and a plurality of ceramic green sheets forouter layers are stacked in this order, and pressed in the stackingdirection to prepare a mother laminated body in the step S3.

Specifically, the mother laminated body is pressed with the use of afirst pressing tool that has a plate-shaped pressing surface and asecond pressing tool that has a pressing surface with a plurality ofrecesses and protrusions. Thereafter, the mother laminated body isfurther pressed with the use of a pair of pressing tools that haveplate-shaped pressing surfaces. In this way, the mother laminated bodycan be prepared which has electrode paste films including a plurality ofrecesses and protrusions.

In addition, the multilayer ceramic capacitor 10 which is able toachieve a greater effect, as shown in FIG. 11, can be obtained byappropriately controlling the type of the glass and the amount of theglass in the base paste which forms the base layers, with regard to thecomposition of the reactive layers. In addition, the reactive layers canbe controlled, as for the thicknesses thereof, by appropriately changingthe baking temperature for the base layers in the step S6.

Specifically, the base paste for use in the formation of the base layersincludes a metal powder and SiO₂—B₂O₃-based glass frit, and the glassfrit preferably contains SiO₂: about 10 weight % to about 50 weight %,B₂O₃: about 10 weight % to about 30 weight %, and V₂O₅: about 1 weight %to about 10 weight % in terms of oxide. The glass frit is preferablycontained at about 0.5 weight % to about 10 weight % with respect to 100weight % of the metal powder.

In addition, the baking temperature for the base layers is preferablyabout 730° C. to about 850° C.

In addition, the multilayer ceramic capacitor 10 which is able toachieve a greater effect, as shown in FIG. 12, can be obtained in such away that t1 to t3 are varied by appropriately controlling, for example,the viscosity of the base paste for forming the base layers 24 a, 24 b,the rate of immersing the ceramic body 12 in the base paste, the rate ofpulling up the body, the condition for drying the base paste, etc., inthe step S5.

In this way, the desired multilayer ceramic capacitor 10 is obtained.

EXPERIMENTAL EXAMPLES

1. Preparation of Evaluation Sample

In the experimental examples, in order to evaluate the externalelectrodes 22 a, 22 b for laser resistance and moisture resistance,evaluation samples of the multilayer ceramic capacitor 10 according toExamples 1 to 3 and Comparative Examples 1 to 6 were prepared bycontrolling the Cu metal of the plated layers 26 a, 26 b respectively topenetrate into the base layers 24 a, 24 b, without control for achievingdesired arithmetic mean roughness (Ra) of the ceramic body 12 in thestep S3 of the manufacturing method mentioned in the previouslydescribed preferred embodiment, control for achieving desired arithmeticmean roughness (Ra) of the external electrodes 22 a, 22 b in the step S7thereof, and controlling for reducing the impurities in the step S8. Theplated layers 26 a, 26 b are entirely composed of Cu plating. In theformation of the Cu plated layers 26 a, 26 b, a pyrophosphoric acid Cuplating solution at pH 8.0 was used in the case of Examples 1 to 3. Onthe other hand, a pyrophosphoric acid Cu plating solution at pH 7.0 wasused in the case of Comparative Examples 1 to 6. Glass containing BaO inan amount of about 10 weight % or more and about 50 weight % or less,SrO in an amount of about 10 weight % or more and about 50 weight % orless, B₂O₃ in an amount of about 3 weight % or more and about 30 weight% or less, and SiO₂ in an amount of about 3 weight % or more and about30 weight % or less was used for the glass in the base layers 24 a, 24b.

Furthermore, the thicknesses of the base layers 24 a, 24 b and Cu platedlayers 26 a, 26 b were controlled by controlling the plating time, etc,in the plating process, so as to have the numerical values listed inTables 1 and 2.

The dimensions of the multilayer ceramic capacitor 10 are about 1.0 mmin dimension in the length direction L, about 0.5 mm in dimension in thewidth direction W, and about 0.15 mm in dimension in the heightdirection T.

2. Confirmation of Penetration of Cu Metal of Cu Plated Layer into BaseLayer

As shown in FIG. 4, in order to confirm whether the Cu metal of the Cuplated layers 26 a, 26 b penetrates into the base layers 24 a, 24 b ornot, the side surface (surface LT) of the multilayer ceramic capacitor10 was polished along the length direction L until reaching about ½ thedimension in the width direction W, and the polished surface wasobserved with an optical microscope. Specifically, with regard to theprincipal surface portion 23 a (base layer 24 a+Cu plated layer 26 a) ofthe external electrode 22 a provided on the first principal surface 12 aof the ceramic body 12 in the polished cross section, the sample wasregarded as “Yes” when the Cu metal of the Cu plated layer 26 apenetrated in the base layer 24 a to a position of about ⅓ or more ofthe thickness of the base layer 24 a from the surface layer of the baselayer 24 a, or regarded as “No” when the Cu metal failed to penetratetherein to a position of about ⅓ or more of the thickness of the baselayer 24 a from the surface layer.

3. Method for Measurement of Physical Thickness of Base Layer and CuPlated Layer

In order to measure the physical thicknesses of the base layers 24 a, 24b and Cu plated layers 26 a, 26 b, the side surface (surface LT) of themultilayer ceramic capacitor 10 was polished along the length directionL until reaching about ½ the dimension in the width direction W, and thepolished surface was observed visually and measured with an opticalmicroscope. Specifically, the thickness was measured in a position ofabout ½ the length of the principal surface portion 23 a (base layer 24a+Cu plated layer 26 a) of the first external electrode 22 a provided onthe first principal surface 12 a of the ceramic body in the polishedcross section. Likewise, the thickness was measured in a position ofabout ½ the length of the principal surface portion 23 c (base layer 24b+Cu plated layer 26 b) of the second external electrode 22 b providedon the first principal surface 12 a of the ceramic body 12 in thepolished cross section. Then, the average of both the measurement valueswas regarded as the physical thicknesses of the base layers 24 a, 24 band Cu plated layers 26 a, 26 b. The measurement values each refer to anaverage value for 50 evaluation samples.

4. Method for Measurement of Metal Thickness of Base Layer and Cu PlatedLayer

In order to measure the metal thicknesses of the base layers 24 a, 24 band Cu plated layers 26 a, 26 b, a fluorescent X-ray film thicknessmeter (SFT-9400 from Seiko Instruments Inc.) was used for themeasurement. In regard to measurement point, the thickness was measured,for example, in a position of a central portion of the principal surfaceportion 23 a (base layer 24 a+Cu plated layer 26 a) of the externalelectrode 22 a. The collimator diameter was about 50 μmφ. Themeasurement time was adjusted to about 1 minute. The data refers to anaverage value for 50 evaluation samples.

5. Method for Evaluation of Laser Resistance

In order to carry out a laser resistance test, a CO₂ laser system(ML605GTX from Mitsubishi Electric Corporation) was used. For example,central portion in each of the length direction L and width direction Wof the principal surface portion 23 a (base layer 24 a+Cu plated layer26 a) of the first external electrode 22 a provided on the firstprincipal surface 12 a of the ceramic body 12 was first irradiated witha single shot of CO₂ laser under the condition of pulse width: about 2μs, frequency: about 4000 Hz, and energy density: about 30 mJ. Next, thepulse width of the CO₂ laser for the irradiation was increased in stagesby about 2 μs up to about 16 μs. As a result, the sample was regarded asNG when a molten mark was generated at the surface of the principalsurface portion 23 a of the first external electrode 22 a, or when abroken mark was generated at the first principal surface 12 a of theceramic body 12.

6. Moisture Resistance Load Test Method

In order to carry out a moisture resistance load test, the multilayerceramic capacitor 10 as an evaluation sample was embedded into amultilayer printed wiring board, and then left for about 400 hours in anair atmosphere at a temperature of about 120° C. and a humidity of about100% RH under application of a voltage of about 6.3 V. Then, theinsulation resistance IR was measured, and when the insulationresistance IR met the condition expression of Log (IR)<5, the sample wasregarded as a failure.

7. Evaluation Result of External Electrode

Table 1 shows evaluation results. In addition, Table 2 is a table thatshows details of the total physical thickness and total metal thicknessof base layer+Cu plated layer shown in Table 1, and shows the individualphysical thickness and metal thickness of the base layer 24 a, 24 b andCu plated layer 26 a, 26 b.

TABLE 1 Comparative Example Comparative Example Comparative ExampleComparative Comparative Comparative Example 1 1 Example 2 2 Example 3 3Example 4 Example 5 Example 6 Penetration of Cu Metal Yes Yes No Yes NoYes No Yes No into Base layer Total Physical Thickness 7.0 10.4 11.915.7 15.5 20.2 18.9 24.3 24.7 of Base layer + Cu Plated Layer (μm) TotalMetal Thickness 6.5 8.7 8.6 11.5 9.5 13.9 11.0 16.4 14.0 of Base layer +Cu Plated Layer (μm) NG Number in Laser 4/50 0/50 7/50 0/50 5/50 0/502/50 0/50 0/50 Resistance Test NG Number in Moisture 0/20 0/20 0/20 0/200/20 0/20 0/20 2/20 3/20 Resistance Load Test NG Percentage in Laser 8  0 14 0  10 0  4  0 0 Resistance Test (%) NG Percentage in Moisture 0   00 0  0 0  0  10 15 Resistance Load Test (%) Comprehensive Evaluation NGOK NG OK NG OK NG NG NG

TABLE 2 Comparative Example Comparative Example Comparative ExampleComparative Comparative Comparative Example 1 1 Example 2 2 Example 3 3Example 4 Example 5 Example 6 Physical Thickness 1.0 3.4 4.9 8.5 9.012.7 11.9 15.8 16.0 of Base layer (μm) Physical Thickness 6.0 7.0 7.07.2 6.5 7.5 7.0 8.5 8.7 of Cu Plated Layer (μm) Metal Thickness of 0.51.7 1.6 4.3 3.0 6.4 4.0 7.9 5.3 Base layer (μm) Metal Thickness of 6.07.0 7.0 7.2 6.5 7.5 7.0 8.5 8.7 Cu Plated Layer (μm)

From Table 1, in the case of Examples 1 to 3 (when the Cu metal of theCu plated layers 26 a, 26 b of the external electrodes 22 a, 22 bpenetrated in the base layers 24 a, 24 b to a position of about ⅓ ormore of the thicknesses of the base layers 24 a, 24 b, and when themetal thicknesses of the external electrodes 22 a, 22 b were about 8.7μm or more and about 13.9 μm or less), the NG percentage in the laserresistance test and the NG percentage in the moisture resistance loadtest were both 0%. Accordingly, the comprehensive evaluations wereregarded as “OK”.

On the other hand, in the case of Comparative Example 1 (when the Cumetal of the Cu plated layers 26 a, 26 b of the external electrodes 22a, 22 b penetrated in the base layers 24 a, 24 b to a position of about⅓ or more of the thicknesses of the base layers 24 a, 24 b from thesurface layers of the base layers 24 a, 24 b, while the externalelectrodes 22 a, 22 b were thin with a metal thickness of about 6.5 μm),the NG percentage in the laser resistance test was about 8%.Accordingly, the comprehensive evaluation was regarded as “NG”.

In the case of Comparative Examples 2 to 4 (when the Cu metal of the Cuplated layers 26 a, 26 b of the external electrodes 22 a, 22 b failed topenetrate in the base layers 24 a, 24 b to a position of about ⅓ or moreof the thicknesses of the base layers 24 a, 24 b from the surface layersof the base layers 24 a, 24 b), the NG percentage in the laserresistance test was about 4% to about 14%. Accordingly, thecomprehensive evaluations were regarded as “NG”.

In the case of Comparative Examples 5 and 6 (when the Cu metal of the Cuplated layers 26 a, 26 b of the external electrodes 22 a, 22 bpenetrated in the base layers 24 a, 24 b to a position of about ⅓ ormore of the thicknesses of the base layers 24 a, 24 b from the surfacelayers of the base layers 24 a, 24 b, while the metal thicknesses of theexternal electrodes 22 a, 22 b were greater than about 13.9 μm), the NGpercentage in the moisture resistance load test was about 10% to about15%. Accordingly, the comprehensive evaluations were regarded as “NG”.

In the preferred embodiments and experimental examples mentioned above,the side surfaces of the ceramic bodies also preferably include externalelectrodes provided thereon, but there is no need to provide theexternal electrodes on the side surfaces of the ceramic bodies.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A multilayer ceramic capacitor comprising: aceramic body including a plurality of ceramic layers and first andsecond internal electrodes stacked, the ceramic body including first andsecond principal surfaces opposed to each other in a height direction,side surfaces opposed to each other in a width direction, and endsurfaces opposed to each other in a length direction; and an externalelectrode including a base layer including metal and glass and a platedlayer provided over a surface of the base layer, the external electrodeprovided over one of the end surfaces and a portion of the firstprincipal surface of the ceramic body, and connected to one of the firstand second internal electrodes at the one of the end surfaces; whereinthe plated layer includes a Cu plated layer including an outermostsurface of the external electrode; and Cu plated materials are presentin the base layer to a position of about ⅓ or more of a thickness of thebase layer from a surface layer of the external electrode; and theexternal electrode is about 8.7 μm or more and about 13.9 μm or less inmetal thickness on average.
 2. The multilayer ceramic capacitoraccording to claim 1, wherein the multilayer ceramic capacitor is about0.9 mm or more and about 1.1 mm or less in length dimension, about 0.4mm or more and about 0.6 mm or less in width dimension, and about 0.085mm or more and about 0.15 mm or less in height dimension.
 3. Themultilayer ceramic capacitor according claim 1, wherein the Cu platedlayer is made through use of one of a pyrophosphoric acid Cu platingsolution and a cyanide Cu plating solution.
 4. The multilayer ceramiccapacitor according to claim 1, wherein the glass contained in the baselayer contains BaO in an amount of about 10 weight % or more and about50 weight % or less, SrO in an amount of about 10 weight % or more andabout 50 weight % or less, B₂ O₃ in an amount of about 3 weight % ormore and about 30 weight % or less, and SiO₂ in an amount of about3weight % or more and about 30 weight % or less, and a total weight ofBaO, SrO, B₂O₃ and SiO₂ is 100 weight %.
 5. The multilayer ceramiccapacitor according to claim 1, wherein a thickness of an effectiveportion that is a portion of the ceramic body where the first and secondinternal electrodes are provided is referred to as A in the thicknessdirection; a thickness of a first outer layer portion that is a portionof the ceramic body located closer to the first principal surface thanthe effective portion is referred to as B in the thickness direction; athickness of a second outer layer portion that is a portion of theceramic body located closer to the second principal surface than theeffective portion is referred to as C in the thickness direction; andeach of ratios A/B and A/C fall within a range of about 0.5 to about 16.6. The multilayer ceramic capacitor according to claim 1, wherein fromone of the first and second internal electrodes located closest to afirst principal surface side of the ceramic body, a maximum value of adistance to the first principal surface of the ceramic body in thethickness direction is T_(MAX); and from the one of the first and secondinternal electrodes located closest to the first principal surface sideof the ceramic body, a minimum value of a distance to the firstprincipal surface of the ceramic body in the thickness direction isT_(MIN); the one of the first and second internal electrodes locatedclosest to the first principal surface is configured such that themultilayer ceramic capacitor is about 0.9 mm or more and about 1.1 mm orless in length dimension, the multilayer ceramic capacitor is about 0.4mm or more and about 0.6 mm or less in width dimension, the multilayerceramic capacitor is about 0.085 mm or more and about 0.11 mm or less inthickness dimension; and a ratio (T_(MAX)−T_(MIN))/T is about 1.0% toabout 5.0%.
 7. The multilayer ceramic capacitor according to claim 1,wherein from one of the first and second internal electrodes locatedclosest to a first principal surface side of the ceramic body, a maximumvalue of a distance to the first principal surface of the ceramic bodyin the thickness direction is T_(MAX); and from the one of the first andsecond internal electrodes located closest to the first principalsurface side of the ceramic body, a minimum value of a distance to thefirst principal surface of the ceramic body in the thickness directionis T_(MiN); the one of the first and second internal electrodes locatedclosest to the first principal surface is configured such that themultilayer ceramic capacitor is about 0.9 mm or more and about 1.1 mm orless in length dimension, the multilayer ceramic capacitor is about 0.4mm or more and about 0.6 mm or less in width dimension, the multilayerceramic capacitor is about 0.012 mm or more and about 0.15 mm or less inthickness dimension; and a ratio (T_(MAX)−T_(MIN))/T is about 1.3% toabout 5.3%.
 8. The multilayer ceramic capacitor according to claim 1,wherein from one of the first and second internal electrodes locatedclosest to a first principal surface side of the ceramic body, a maximumvalue of a distance to the first principal surface of the ceramic bodyin the thickness direction is T_(MAX); and from the one of the first andsecond internal electrodes located closest to the first principalsurface side of the ceramic body, a minimum value of a distance to thefirst principal surface of the ceramic body in the thickness directionis T_(MIN); the one of the first and second internal electrodes locatedclosest to the first principal surface is configured such that themultilayer ceramic capacitor is about 0.9 mm or more and about 1.1 mm orless in length dimension, the multilayer ceramic capacitor is about 0.4mm or more and about 0.6 mm or less in width dimension, the multilayerceramic capacitor is about 0.018 mm or more and about 0.20 mm or less inthickness dimension, and a ratio (T_(MAX)−T_(MIN))/T is about 1.5% toabout 5.0%.
 9. The multilayer ceramic capacitor according to claim 1,wherein from one of the first and second internal electrodes locatedclosest to a first principal surface side of the ceramic body, a maximumvalue of a distance to the first principal surface of the ceramic bodyin the thickness direction is T_(MAX); and from the one of the first andsecond internal electrodes located closest to the first principalsurface side of the ceramic body, a minimum value of a distance to thefirst principal surface of the ceramic body in the thickness directionis T_(MIN); the one of the first and second internal electrodes locatedclosest to the first principal surface is configured such that themultilayer ceramic capacitor is about 0.9 mm or more and about 1.1 mm orless in length dimension, the multilayer ceramic capacitor is about 0.4mm or more and about 0.6 mm or less in width dimension, the multilayerceramic capacitor is about 0.021 mm or more and about 0.23 mm or less inthickness dimension; and a ratio (T_(MAX)−T_(MIN))/T is about 1.8% toabout 5.9%.
 10. The multilayer ceramic capacitor according to claim 1,wherein from one of the first and second internal electrodes locatedclosest to a first principal surface side of the ceramic body, a maximumvalue of a distance to the first principal surface of the ceramic bodyin the thickness direction is T_(MAX); and from the one of the first andsecond internal electrodes located closest to the first principalsurface side of the ceramic body, a minimum value of a distance to thefirst principal surface of the ceramic body in the thickness directionis T_(MIN); the one of the first and second internal electrodes locatedclosest to the first principal surface is configured such that themultilayer ceramic capacitor is about 0.9 mm or more and about 1.1 mm orless in length dimension, the multilayer ceramic capacitor is about 0.4mm or more and about 0.6 mm or less in width dimension, the multilayerceramic capacitor is about 0.024 mm or more and about 0.30 mm or less inthickness dimension, and a ratio (T_(MAX)−T_(MIN))/T is about 1.2% toabout 6.0%.
 11. The multilayer ceramic capacitor according to claim 1,wherein a maximum thickness of a portion of the external electrodelocated on the one of the end surfaces is t1 in a cross section passingthrough a center in the width direction and extending in the lengthdirection and the thickness direction; a maximum thickness of a portionof the external electrode located on the first principal surface is t2in a cross section passing through the center in the width direction andextending in the length direction and the thickness direction; and athickness of the external electrode on a line passing through a point ofintersection between a tangent line on a corner of the ceramic body, andthe corner and the point of intersection between a line along the firstprincipal surface and a line along the one of the end surfaces is t3 ina cross section passing through the center in the width direction andextending in the length direction and the thickness direction; in themultilayer ceramic capacitor, a ratio t2/t1 is about 0.7 to about 1.0,and a ratio t3/t1 is about 0.4 to about 1.2.
 12. The multilayer ceramiccapacitor according to claim 1, wherein the external electrode of themultilayer ceramic capacitor is configured such that when a distancefrom a position of a maximum thickness on the first principal surface ofthe ceramic body to a position of a maximum thickness on the one of theend surfaces of the ceramic body is a dimension Ed; and a distance froma position of a maximum thickness on the one of the end surfaces of theceramic body to an edge end of the external electrode on the firstprincipal surface of the ceramic body is referred to as a dimension e;and a ratio Ed/e is about 0.243 or more and about 0.757 or less.
 13. Themultilayer ceramic capacitor according to claim 1, wherein a maximumthickness and an average thickness of a portion of the externalelectrode located on the principal surfaces of the ceramic body aredenoted respectively by D_(max) and D_(ave); and D_(ave×)250%≧D_(max)≧D_(ave×)120% is satisfied.
 14. The multilayer ceramic capacitoraccording to claim 1, wherein each of the plurality of ceramic layers isabout 0.5 μm or more and about 10 μm or less in height.
 15. Themultilayer ceramic capacitor according to claim 1, wherein each of thefirst internal electrode and the second internal electrode is about 0.2μm to about 2 μm in height.
 16. The multilayer ceramic capacitoraccording to claim 1, wherein the base layer is about 1 μm to about 20μm in thickness.
 17. The multilayer ceramic capacitor according to claim1, wherein the Cu plated layer is about 1 μm to about 10 μm inthickness.
 18. The multilayer ceramic capacitor according to claim 1,wherein the Cu plated layer includes a plurality of plated films.
 19. Anelectronic component comprising: a multilayer printed wiring board; andthe multilayer ceramic capacitor according to claim 1 embedded in themultilayer printed wiring board.
 20. The electronic component accordingto claim 19, wherein a via hole is provided in the multilayer printedwiring board to provide electrical connection to the multilayer ceramiccapacitor.